/**
 * @param {Function} func
 * @param {number} wait
 * @param {boolean} immediate
 * @return {*}
 */
export function debounce(func, wait, immediate) {
  let timeout, args, context, timestamp, result

  const later = function() {
    // 据上一次触发时间间隔
    const last = +new Date() - timestamp

    // 上次被包装函数被调用时间间隔 last 小于设定时间间隔 wait
    if (last < wait && last > 0) {
      timeout = setTimeout(later, wait - last)
    } else {
      timeout = null
      // 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
      if (!immediate) {
        result = func.apply(context, args)
        if (!timeout) context = args = null
      }
    }
  }

  return function(...args) {
    context = this
    timestamp = +new Date()
    const callNow = immediate && !timeout
    // 如果延时不存在，重新设定延时
    if (!timeout) timeout = setTimeout(later, wait)
    if (callNow) {
      result = func.apply(context, args)
      context = args = null
    }

    return result
  }
}
/**
 * 像素转rem单位
 * @param {Number} num
 * @return {*}
 */
export function toRem(num) {
  let clientWidth = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth
  if (!clientWidth) return
  let fontSize = clientWidth / 375
  return num * fontSize
}
/**
 * HEX十六进制颜色值转换为RGB(A)颜色值
 * @param {Number} hexColor
 * @param {String} opacity
 * @return {*}
 */
export function toRGBAColor(hexColor, opacity) {
  let r; let g; let b
  if ((/^#/g).test(hexColor)) {
    r = hexColor.slice(1, 3)
    g = hexColor.slice(3, 5)
    b = hexColor.slice(5, 7)

    if (opacity) {
      return 'rgb(' + parseInt(r, 16) + ',' + parseInt(g, 16) + ',' + parseInt(b, 16) + ',' + opacity + ')'
    }
    return 'rgb(' + parseInt(r, 16) + ',' + parseInt(g, 16) + ',' + parseInt(b, 16) + ')'
  } else {
    return hexColor
  }
}
